CREATE OPERATOR CLASS(7)                                  SQL Commands                                  CREATE OPERATOR CLASS(7)



NAME
       CREATE OPERATOR CLASS - define a new operator class


SYNOPSIS
       CREATE OPERATOR CLASS name [ DEFAULT ] FOR TYPE data_type
         USING index_method [ FAMILY family_name ] AS
         {  OPERATOR strategy_number operator_name [ ( op_type, op_type ) ]
          | FUNCTION support_number [ ( op_type [ , op_type ] ) ] funcname ( argument_type [, ...] )
          | STORAGE storage_type
         } [, ... ]


DESCRIPTION
       CREATE  OPERATOR  CLASS  creates  a new operator class.  An operator class defines how a particular data type can be used
       with an index. The operator class specifies that certain operators will fill particular roles or ``strategies'' for  this
       data  type and this index method. The operator class also specifies the support procedures to be used by the index method
       when the operator class is selected for an index column. All the operators and functions used by an operator  class  must
       be defined before the operator class can be created.

       If a schema name is given then the operator class is created in the specified schema. Otherwise it is created in the cur-
       rent schema.  Two operator classes in the same schema can have the same name only if they are for different  index  meth-
       ods.

       The  user  who  defines  an  operator  class  becomes  its owner. Presently, the creating user must be a superuser. (This
       restriction is made because an erroneous operator class definition could confuse or even crash the server.)

       CREATE OPERATOR CLASS does not presently check whether the operator class definition includes all the operators and func-
       tions  required by the index method, nor whether the operators and functions form a self-consistent set. It is the user's
       responsibility to define a valid operator class.

       Related operator classes can be grouped into operator families. To add a new operator class to an existing family,  spec-
       ify the FAMILY option in CREATE OPERATOR CLASS. Without this option, the new class is placed into a family named the same
       as the new class (creating that family if it doesn't already exist).

       Refer to in the documentation for further information.

PARAMETERS
       name   The name of the operator class to be created. The name can be schema-qualified.

       DEFAULT
              If present, the operator class will become the default operator class for its data  type.  At  most  one  operator
              class can be the default for a specific data type and index method.

       data_type
              The column data type that this operator class is for.

       index_method
              The name of the index method this operator class is for.

       family_name
              The name of the existing operator family to add this operator class to.  If not specified, a family named the same
              as the operator class is used (creating it, if it doesn't already exist).

       strategy_number
              The index method's strategy number for an operator associated with the operator class.

       operator_name
              The name (optionally schema-qualified) of an operator associated with the operator class.

       op_type
              In an OPERATOR clause, the operand data type(s) of the operator, or NONE to signify a  left-unary  or  right-unary
              operator. The operand data types can be omitted in the normal case where they are the same as the operator class's
              data type.

              In a FUNCTION clause, the operand data type(s) the function is intended to support, if different  from  the  input
              data  type(s)  of  the function (for B-tree and hash indexes) or the class's data type (for GIN and GiST indexes).
              These defaults are always correct, so there is no point in specifying op_type in a FUNCTION clause in CREATE OPER-
              ATOR CLASS, but the option is provided for consistency with the comparable syntax in ALTER OPERATOR FAMILY.

       support_number
              The index method's support procedure number for a function associated with the operator class.

       funcname
              The  name  (optionally  schema-qualified) of a function that is an index method support procedure for the operator
              class.

       argument_types
              The parameter data type(s) of the function.

       storage_type
              The data type actually stored in the index. Normally this is the same as the column  data  type,  but  some  index
              methods  (currently  GIN  and  GiST) allow it to be different. The STORAGE clause must be omitted unless the index
              method allows a different type to be used.

       The OPERATOR, FUNCTION, and STORAGE clauses can appear in any order.

NOTES
       Because the index machinery does not check access permissions on functions before using them,  including  a  function  or
       operator in an operator class is tantamount to granting public execute permission on it. This is usually not an issue for
       the sorts of functions that are useful in an operator class.

       The operators should not be defined by SQL functions. A SQL function is likely to be  inlined  into  the  calling  query,
       which will prevent the optimizer from recognizing that the query matches an index.

       Before PostgreSQL 8.4, the OPERATOR clause could include a RECHECK option. This is no longer supported because whether an
       index operator is ``lossy'' is now determined on-the-fly at runtime. This allows efficient handling  of  cases  where  an
       operator might or might not be lossy.

EXAMPLES
       The  following  example  command  defines  a  GiST index operator class for the data type _int4 (array of int4). See con-
       trib/intarray/ for the complete example.

       CREATE OPERATOR CLASS gist__int_ops
           DEFAULT FOR TYPE _int4 USING gist AS
               OPERATOR        3       &&,
               OPERATOR        6       = (anyarray, anyarray),
               OPERATOR        7       @>,
               OPERATOR        8       <@,
               OPERATOR        20      @@ (_int4, query_int),
               FUNCTION        1       g_int_consistent (internal, _int4, int, oid, internal),
               FUNCTION        2       g_int_union (internal, internal),
               FUNCTION        3       g_int_compress (internal),
               FUNCTION        4       g_int_decompress (internal),
               FUNCTION        5       g_int_penalty (internal, internal, internal),
               FUNCTION        6       g_int_picksplit (internal, internal),
               FUNCTION        7       g_int_same (_int4, _int4, internal);


COMPATIBILITY
       CREATE OPERATOR CLASS is a PostgreSQL extension. There is no CREATE OPERATOR CLASS statement in the SQL standard.

SEE ALSO
       ALTER OPERATOR CLASS [alter_operator_class(7)], DROP OPERATOR  CLASS  [drop_operator_class(7)],  CREATE  OPERATOR  FAMILY
       [create_operator_family(7)], ALTER OPERATOR FAMILY [alter_operator_family(7)]



SQL - Language Statements                                  2011-09-22                                   CREATE OPERATOR CLASS(7)